Abstract:

The atoms in conventional (i.e. alkai) atomic Bose-Einstein  condensates interact via
short-range s-wave interactions which decay as 1/r ⁶ (van der Waals  interactions).
However, recently a BEC of chromium atoms was made by T. Pfau's group  in Stuttgart [PRL
94, 160401 (2005)]. Chromium has an anomalously large magnetic dipole  moment and
consequently a chromium BEC has large dipole-dipole interactions.  There are also many
efforts going on worldwide to make ultracold polar molecules which  have potentially huge
dipole moments. In this talk I will introduce the theory of trapped  dipolar condensates
and compare it to the results of experiments conducted so far. We  shall see how the
long-range and anisotropic form of the dipole-dipole interaction leads  to new mesoscopic
effects which depend on the shape of the condensate surface. These include
magnetotstriction and an instability towards the formation of a  density wave. Finally, I
will dicuss the role of the sign of the interactions in controlling  the properties of
these novel superfluids under rotation.